The present invention is directed generally to thermoelectric assemblies, and in particular, to a sealing member for the thermoelectric module of a thermoelectric assembly.
Thermoelectric assemblies are solid state heat pumps that extract or add heat to an object or region, and so can be used for cooling or heating, depending on the specific application. They can also be used to generate electrical current. Such thermoelectric assemblies are currently used in a wide variety of applications in order to affect the thermal environment of a particular object or region. In its broadest form, a thermoelectric assembly includes a cold side heat exchanger, or xe2x80x9ccold sinkxe2x80x9d, and a hot side heat exchanger or xe2x80x9cheat sinkxe2x80x9d. A thermoelectric module, often referred to as a Peltier Effect Module, is positioned or sandwiched between the inner surfaces of both the cold sink and the heat sink. The thermoelectric module uses electrical current to create a temperature difference between the heat sink and cold sink, or can generate electrical current from an imposed temperature difference between the heat sink and cold sink.
Variations in, and additions to, the basic components enable a thermoelectric assembly to be tailored to a specific application. For example, when used to cool air in electronic enclosures, medical cabinets, small refrigerators, environmental chambers, battery boxes, mini-bars, picnic boxes, or vending machines, thermoelectric assemblies are referred to xe2x80x9cair-to-air coolersxe2x80x9d and include a fan attached to both the heat sink and the cold sink. The cold sink is positioned within the region to be cooled such as the interior of a refrigerator, while the heat sink is positioned exterior to the controlled region. Air is drawn into the assembly by the fan attached to the cold sink and recirculates cooled air within the controlled region, while the fan attached to the heat sink draws in ambient air and exhausts heated air to the external environment.
In xe2x80x9cplate-to-airxe2x80x9d type thermoelectric assemblies, often used in conjunction with laser diodes, CPU coolers, liquid reservoirs, temperature baths, water coolers, gene cloning equipment, aquariums, and beverage coolers, the cold sink is in the form of a plate which is in direct thermal and/or mechanical contact with the region to be cooled.
In still another form, thermoelectric assemblies are referred to as xe2x80x9cplate-to-platexe2x80x9d and are used, for example, in detectors, sensors, CCD""s, small laser diodes, integrated circuits, and lamps, both the hot and cold sink are plates. The object or region is cooled with direct contact to the cold plate, while the plate-style heat exchanger on the hot side is attached to a secondary heat sink.
In xe2x80x9cliquid-to-airxe2x80x9d thermoelectric assemblies, a serpentine-shaped liquid conduit is attached to the cold plate. Heated fluid travels into the input of the liquid conduit, and heat exchange is accomplished while the conduit is in contact with the cold plate. The fluid outlet of the liquid conduit transports the cooled fluid to a region in which it is utilized, while heat is exhausted by the heat sink. Such liquid-to-air thermoelectric assemblies are utilized in, for example, therapy pads for medical treatment, laser chillers, cooling process fluids, temperature baths, and semi-conductor processing equipment.
The reliability of all types of thermoelectric modules and also the efficiency of the thermoelectric assembly is dependent upon its ability to effectively transfer heat between the cold sink and the heat sink. This ability is severely compromised by the introduction of water vapor to the thermoelectric module. Specifically, when water vapor is allowed to condense within the thermoelectric module, interaction between the condensed water and the thermoelectric module causes the module to corrode, and over time, leads to catastrophic failure. Thus, it is critical that an effective hermetic seal be formed about the thermoelectric module.
Existing sealing methods are ineffective for a variety of reasons. In many designs, a seal is achieved by the use of some form of sealing agent surrounding the thermoelectric module. The sealing agents, over time, given their chemical composition, are susceptible to degradation, which will eventually permit water vapor to penetrate the seal and deleteriously impact the thermoelectric module. Also, some thermoelectric assemblies employ an O-ring having apertures formed to accept the electrical wires necessary to power the thermoelectric module. These wires are stranded, and as such permit the intrusion of vapor through the interstices formed between the stranded wires. Also, in order to secure the thermoelectric module between the cold sink and the heat sink, fasteners are employed to provide a secure connection. Often, the fasteners used to secure the particular components of the thermoelectric assembly are positioned through the sealing agents or O-rings. Alternatively, such fasteners are located within the area defined between the inner surface of the sealing agent or O-ring, and the thermoelectric module. These fasteners require the use of an annulus or aperture in which they are fitted, and due to manufacturing tolerances, provide intrusion sites through which water vapor may penetrate and eventually condense at the thermoelectric module. Still further, other sealing methods, given their structure and configuration, are cost prohibitive.
Consequently, there exists a need within the industry for a sealing member for a thermoelectric assembly which provides a reliable, effective hermetic seal about the thermoelectric module, and which is cost effective to manufacture.
According to one aspect of the invention, a sealing member for a thermoelectric assembly having a thermoelectric module with a periphery and at least one wire projecting therefrom, and positioned between a first heat exchanger and a second heat exchanger comprises an elastomeric member, having a low water vapor permeability, and configured to sealingly engage the first heat exchanger and the second heat exchanger, and is adapted to be positioned beyond the periphery of the thermoelectric module. The elastomeric member has a first surface adapted to engage a surface of the first heat exchanger and an opposing second surface, adapted to engage a surface of the second heat exchanger. Each surface of the elastomeric member is formed with at least one peripheral channel. At least one aperture is formed within the elastomeric member and is dimensioned to sealingly receive the wire from the thermoelectric module. The at least one aperture has a substantially uniform cross section.
The utilization of an elastomeric material having a low water permeability increases the reliability of the sealing member. Furthermore, the peripheral channels formed within the elastomeric member provide capturing sites which effectively trap water vapor and prevent the same from migrating towards the thermoelectric module. Moreover, the uniform cross-section of the aperture increases the reliability of the seal between the aperture and the wire.
According to yet another aspect of the invention, a thermoelectric assembly includes a thermoelectric module having a pair of opposing surfaces, a periphery, and at least one electrical wire projecting therefrom. The thermoelectric module is positioned between a first and second heat exchanger, while a sealing member is positioned beyond the periphery of the thermoelectric module. The sealing member has a first sealing surface which sealingly engages the first heat exchanger, and a second sealing surface which sealingly engages the second heat exchanger. The sealing member is formed with at least one aperture having a generally uniform cross-section, and is dimensioned to receive the at least one electrical wire projecting from the thermoelectric module. A wire guide projects from the sealing member in a direction away from the thermoelectric module, and has a central channel. The central channel is substantially axially aligned with the aperture, and is dimensioned to receive the at least one wire.
Providing a wire guide projecting from the sealing member increases the distribution of forces exerted on the wire across a greater surface area. As the forces exerted on the wire are distributed over a greater surface, there is less of a tendency for the wire to move in a direction normal to the axial direction of the central channel and thus create an interstice between the channel and the wire through which vapor may penetrate.
According to still another aspect of the invention, a thermoelectric assembly includes a thermoelectric module positioned between a first and second heat exchanger. A sealing member is positioned about the periphery of the thermoelectric module and sealingly engages the inner surface of the first and second heat exchanger. At least one fastener extends between the first and second heat exchanger and is positioned beyond the outer surface of the sealing member.
Positioning the at least one fastener beyond the outer surface of the sealing member eliminates the probability for the intrusion of water vapor due to placement of the fastener within the area defined between the thermoelectric module and the inner surface of the sealing member, or the placement of a fastener through the sealing member itself.
According to still a further aspect of the invention, a thermoelectric assembly includes a thermoelectric module positioned between a first and second heat exchanger. The thermoelectric module has at least one wire projecting therefrom, the wire having a section surrounded by a polymeric material. A sealing member is positioned about the periphery of the thermoelectric module and has a pair of sealing surfaces which engage the first and second heat exchanger. The sealing member is formed with an aperture dimensioned to receive the at least one wire. The aperture defines a wall therearound and the polymeric material is molded to the wall. Molding the polymeric material which surrounds at least a section of the wire to the wall of the sealing member increases the sealing engagement therebetween and prevents water vapor from passing therethrough and impacting the thermoelectric module.
In another aspect of the invention, a thermoelectric assembly employs an electrical connector member molded directly to the aperture of the sealing member. In this embodiment, the at least one wire of the thermoelectric assembly is connected to the electrical connector member.
According to a further aspect of the invention, a sealing member for a thermoelectric assembly having a thermoelectric module with a periphery and at least one wire projecting therefrom, and positioned between a first heat exchanger and a second heat exchanger comprises an elastomeric member, having a low water vapor permeability, and configured to sealingly engage the first heat exchanger and the second heat exchanger, and is adapted to be positioned beyond the periphery of the thermoelectric module. The elastomeric member has first surface adapted to engage a surface of the first heat exchanger and an opposing second surface adapted to engage a surface of the second heat exchanger. At least one aperture is formed within the elastomeric member and is dimensioned to sealingly receive the at least one wire. Additionally, the elastomeric member is formed having a thermally insulative filler material homogeneously disbursed therein. This thermally insulative filler material reduces the heat loss through the elastomeric member and increases the efficiency of the thermoelectric assembly.
According to yet a further aspect of the invention, a sealing member for a thermoelectric assembly having a thermoelectric module with a periphery and at least one wire projecting therefrom, and positioned between a first heat exchanger and a second heat exchanger comprises an elastomeric member, having a low water vapor permeability, and configured to sealingly engage the first heat exchanger and the second heat exchanger. The sealing member is adapted to be positioned beyond the periphery of the thermoelectric module. The elastomeric member is formed with a central channel and has a first surface adapted to engage a surface of the first heat exchanger and an opposing second surface, adapted to engage a surface of the second heat exchanger. At least one aperture is formed within the elastomeric member and is dimensioned to sealingly receive the at least one wire. The central channel of the elastomeric member provides a thermally insulative barrier, and reduces the heat loss across the sealing member which in turn increases the efficiency of the thermoelectric assembly.
Yet another form of the sealing member may include one or more indexing guides which receive fasteners from the thermoelectric assembly and facilitate proper positioning of the sealing member in the assembly.
These and other objects, advantages, purposes and features of the invention will become apparent upon review of the following specification in conjunction with the drawings.